From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752339Ab0EOHqL (ORCPT ); Sat, 15 May 2010 03:46:11 -0400 Received: from mail-ew0-f216.google.com ([209.85.219.216]:46863 "EHLO mail-ew0-f216.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750771Ab0EOHqJ (ORCPT ); Sat, 15 May 2010 03:46:09 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:date:from:to:cc:subject:message-id:in-reply-to:references :x-mailer:mime-version:content-type:content-transfer-encoding; b=nVufhDVqWH7oPScFIUpO8BROatRuSenqKiWvEDj1Yo6QG3hCAWWj65iNVLF403ewNN yuRKBdOxEgseaQtEJpeee8MikEvDKCZMFWrGs7hcp2e+04Edrm/jq6Yjkwx0WgUzWLY4 iAXm9hqDEgFM0q8sUPB9J7cbAVMcCNY8+Iiag= Date: Sat, 15 May 2010 10:46:02 +0300 From: Pekka Paalanen To: rostedt@goodmis.org Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Frederic Weisbecker , Larry Finger Subject: Re: [PATCH 3/4] tracing: Allow mmio tracer to display trace_printk() and other events Message-ID: <20100515104602.59c1f0e1@daedalus.pq.iki.fi> In-Reply-To: <1273763483.27703.991.camel@gandalf.stny.rr.com> References: <20100513012110.558313399@goodmis.org> <20100513012302.352845720@goodmis.org> <20100513115414.7688b51d@daedalus.pq.iki.fi> <1273752909.27703.809.camel@gandalf.stny.rr.com> <20100513152915.3d3f852b@daedalus.pq.iki.fi> <1273763483.27703.991.camel@gandalf.stny.rr.com> X-Mailer: Claws Mail 3.7.5 (GTK+ 2.18.7; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry, I'm not at my email every day. Real life... On Thu, 13 May 2010 11:11:23 -0400 Steven Rostedt wrote: > On Thu, 2010-05-13 at 15:29 +0300, Pekka Paalanen wrote: > > On Thu, 13 May 2010 08:15:09 -0400 > > > > It only displays other events if the user enabled those > > > events. > > > > > > But that said, I don't want to break existing userspace > > > tools. I can add a mmiotrace option "mmiotrace_all_events", > > > if the user wants to see all events within the mmiotracer > > > then they can just enable that option, otherwise, the > > > mmiotracer will act like it currently does. > > > > > > How does that sound? > > > > That would be fine. Is it not redundant with what you said in > > your first sentence? > > > > Right now with this patch as is. When you enable the mmiotracer it > clears the ring buffer. But if someone previously enabled an > event (like sched_switch for example) then that event will appear > in the output of the tracer. > > The user will need to disable that event and restart the > mmiotracer so the output will not break the userspace tools. Is > this OK? I think it is ok. No non-mmiotrace events are enabled automatically, right? Except perhaps trace_printk()? If a user enables other events while mmiotracing, I would assume he knows what he is doing. End users doing dumps per request never even know about other kinds of tracing than mmiotrace. > If not, then my suggestion is to have an mmiotracer option that > keeps it from printing out any event except for the ones it knows > about. > > The reason I added this patch in the first place was because Larry > Finger was using the mmiotrace with trace_printk() and the > current code does not print out the trace_printk() when > mmiotracer is active. If this is *only* about trace_printk(), why not make a handler for it to emit MARK lines? Actually, I somehow assumed that would have been the case, but apparently the event type is different. I do not recall these things too well anymore. Thanks for keeping me in the loop. -- Pekka Paalanen http://www.iki.fi/pq/